Annual Research & Review in Biology

36(6): 46-54, 2021; Article no.ARRB.69680 ISSN: 2347-565X, NLM ID: 101632869

Occurrence, Distribution and Identification of Viruses Infecting Some Cucurbits Across Major Cucurbit-Growing Areas in Cross River State, Nigeria

O. I. Eyong1*, E. E. Ekpiken2 and O. A. Iso2

1Department of Forestry Wildlife Managment, Cross River University of Technology, Calabar, Nigeria. 2Department of and Biotechnology, Cross River University of Technology, Calabar, Nigeria.

Authors’ contributions

This work was carried out in collaboration among all authors. Author OIE designed the study, wrote the protocol and wrote the first draft of the manuscript. Authors EEE managed the analyses of the study. Author OAI read the first draft of the manuscript. All authors read and approved the final manuscript

Article Information

DOI: 10.9734/ARRB/2021/v36i630389 Editor(s): (1) Dr. Manikant Tripathi, Dr. Ram Manohar Lohia Avadh University, India. Reviewers: (1) Justus Eronmosele Omijeh, Modibbo Adama University of Technology,Yola, Nigeria. (2) J. O. Cheikyula, Joseph Sarwuan Tarka University, Nigeria. Complete Peer review History: http://www.sdiarticle4.com/review-history/69680

Received 06 April 2021 Original Research Article Accepted 13 June 2021 Published 23 June 2021

ABSTRACT

Cucurbits are group of which belonged in the family and constitute one of the most important vegetables for human consumption throughout the world. A survey conducted between January to March 2021 across major cucurbit-growing area in Cross River State revealed wide spread virus infection of these crops, surveyed plants showed mosaic, mottle and leaf deformation symptoms. This research was aimed at identifying viruses infecting some cucurbits in the study areas. Twenty four samples showing virus like symptoms were collected and tested against ACP-ELISA and RT-PCR. Result obtained from ACP-ELISA showed that 20 out of 24 samples collected tested positive to universal potyvirus antisera, the gene sequence analysis revealed that samples were predominantly infected with Algerian mosaic virus representing 40% of total viruses detected followed by Morroccan watermelon mosaic virus representing 15% of total viruses detected followed by Papaya ringspot virus, Zucchini tigre mosaic virus, Watermelon mosaic virus and Soybean mosaic virus representing 10% each for total viruses detected and finally Potato virus Y representing 5% of total virus detected. This survey is an ______

*Corresponding author: E-mail: [email protected];

Eyong et al.; ARRB, 36(6): 46-54, 2021; Article no.ARRB.69680

accurate and timely detection and will form the basis for mitigating yield losses resulting from virus infection on cucurbits. This is the first report of wide scale detection of viruses infecting cucurbits in Nigeria.

Keywords: Cucurbitaceae; ACP-ELISA; RT-PCR; potyvirus; antisera.

1. INTRODUCTION and squash, while the USA is the main producer in the Western Hemisphere with Cucurbits represent one of the most important 4,602,370 tons [1]. Cucurbit crops are often vegetables for human consumption throughout threatened by diseases of fungal, bacterial and the world. Cucurbit are members of the viral origin [2] and pests, such as the pumpkin family Cucurbitaceae that roughly includes 120 ( spp.) and the fly genera and 800 species, which are (Bactrocera cucurbitae Coquillet), are also predominantly tropical plants though some, such serious constraints to their cultivation [3,4,5]. as four major cucurbit crops are economically Aphids, whiteflies and thrips can become serious important worldwide: melon ( melo L.), limitations to cucurbit production through the cucumber (Cucumis sativus L.), watermelon extensive damage they provoke, but also through ( lanatus (Thumb.) Mat. & Nak.), squash the transmission of viral disease [6,7,8]. At least and pumpkin (Cucurbita spp.) [1]. Global 59 viruses infecting cucurbits are known [9], production of cucurbits cultivated in the world is whose outbreaks have led to significant yield 151,212,210 tons. is the main producer losses worldwide [6,10,11]. with 83,429,409 tons of melon, watermelon,

a B C

d E F

g H

Fig. 1 (a-h). a- Mosaic and chlorotic spot on Cucurbita pepo, b-Rugosity and mottle on Zeneria sp, c- Leaf malformation and mosaic on watermelon, d- Mosaic, green vein banding and leaf malformation on cucumber, e- leaf malformation/deformation and chlorosis on Telfairia occidental, f-Mosaic and leaf deformation on Cucurbita moschata, g-Chlorotic spots on , h-Mosaic on Lagenaria siceraria

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The most commonly encountered of 2. MATERIALS AND METHODS these viruses of cucurbits are Papaya ringspot virus-W (PRSV-W), Squash leaf curl virus 2.1 Sources and Isolation of Viruses (SLCuV), Soybean mosaic virus (SMV), Squash mosaic virus (SqMV) and Squash vein Twenty-four (24) samples with typical virus-like yellowing virus (SqVYV). Others include symptoms were collected from different cucurbit Tobacco ringspot virus (TRSV), Watermelon crops, which included Telfairia occidentalis, mosaic virus (WMV), Watermelon silver Cucumis sativus, Cucurbita pepo, Lagenaria mottle virus (WSMoV), Alfalfa mosaic virus siceraria, Citrullus lanatus, Zehneria spp, (AMV), Bean pod mottle virus (BPMV), Cucumeropsis mannii, Momordica charantia and Cucurbit aphid borne yellows virus Cucurbita moschata. These cucurbits were found (CABYV), Cucurbit yellow stunting disorder growing on farms and gardens in Calabar, virus (CYSDV), Cucumber green mottle Baccocco, Akamkpa, Ehom, Akpet, Abini, Adim, mosaic virus (CGMMV), Cucumber mosaic virus Iwuru in Southern Ekori, Nko, Mkpani, Ofodua, (CMV), Melon necrotic spot virus Ofatura, Okuni, Ikom, Ugep in Central and Afrike, (MNSV), Zucchini yellow mosaic virus Alege, I gwo, Igoli, Okuku, Sankwala, Basang and (ZYMV), and Zucchini green mottle mosaic virus Udeshi in Northern Cross River State, Nigeria. (ZGMMV). These viruses have emerged as the Infected leaf samples were collected into Ziploc most economically significant viruses air tight polyethylene bags to keep them fresh to infecting cucurbits in various cucurbit-growing ensure the viability of the viruses and later regions of the globe [10]. Of these viruses CMV, transported to the Molecular Laboratory of SqMV, WMV-1 (now renamed WMV), National Institute of Horticulture Ibadan, Nigeria WMV-2, ZYMV beside SqMV which is for serology and molecular testing while the seedborne in melon are transmitted by sequencing was done at Inqaba Biotech West beetles. Others are transmitted mechanically and (IBWA), Ibadan, Nigeria. by several aphid species in a non persistent manner [2]. Only very few of these viruses have been characterized and 2.2 Serological Tests identified in Nigeria. For example, [12] have reported infection of fluted pumpkin by Antigen coated plate enzyme linked Cucumber mosaic virus in northern Nigeria, immunosorbent assay (ACP-ELISA) as [13] have also characterized and reported described by [16] was used to determine the Yam mosaic virus (YMV) and Telfairia genus to which the virus isolates belonged. mosaic virus (TeMV) infecting cucurbits in Symptomatic leaf samples of 0.1g were triturated Northern Nigeria. [14] havefurther in 1mL of coating buffer (0.015M Na2 Co3 + provided a checklist of viruses prevalent in 0.0349 M NaHCo3 + dH2O) and dispensed into south west of Nigeria [15] also reported each well of ELISA plate. After incubation at infection of cucumber by Papaya Ringspot 37°C for 1h the plate was washed 3 times with virus (PRSV) and infection of Cucurbita PBS-Tween for 3 min between each wash. Cross moschata by Morroccan watermelon mosaic adsorption was made by grinding 1 g of healthy virus (MWMV) in Calabar Southern Nigeria. plant sample in 20mL of conjugate buffer (1/2 However, Information regarding large scale PBS + 0.05% Tween 20 + 0.02% egg albumin + infection of cucurbits in Southern Nigeria is 0.2% PVP). Universal potyvirus and lacking hence this study. A visit to some cucurbit Cucumovirus antisera were diluted at 1:3000 in growing farms in these areas between January to the adsorption solution and 100μL of each March 2021 revealed widespread infection of antiserum polyclonal antisera was added to wells these crops. Infected plants exhibited a wide of the ELISA plates and again incubated at 37°C range of virus-like symptoms such as for 1hour. The ELISA plates were then washed 3 mosaic, chlorotic spots, mottling, leaf times with PBS-Tween. One hundred-μL of malformation/deformation and leaf reduction, protein, A-alkaline phosphatase conjugate diluted some of which are presented in Fig. 1 (a-h). This in the ratio 1:15000 in conjugate buffer (1/2 PBS research was therefore designed to carry out a + 0.05% Tween 20 + 0.02% egg albumin + 0.2% survey on potyviruses infecting some PVP + 0 .02g NaNO3) was added per well and the cucurbits across different regions in Cross River plates incubated at 37°C for 1h. The plates were again washed 3 times with PBS-Tween. One State Nigeria, employing serological and -1 molecular tools with a view to identifying hundred -μL of 0.001g∙mL of p-nitrophenyl them. phosphate substrate in substrate buffer (97mL

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diethanolamine + 800mL H2O + 0.2g NaNO3 and min. Then 250 μL of 6M potassium acetate (pH HCl to give pH 9.8) was added per well and 6.5) were added and the tubes were transferred incubated at room temperature for 1 h. For all on ice for 20 min. After centrifugation, nucleic incubations, plates were covered with ELISA acids were precipitated with 500 μL ethanol. The cover plates to avoid edge effects and to pellet was resuspended in 50 μL RNAse free maintain uniform temperature. Healthy plant sterile water. samples were used as controls. After 1 h absorbance was measured at A405nm using an 2.4 RT-PCR ELISA plate reader (Micro Read 1000 ELISA plate analyser, U.S.A) after 1 h of incubation. RT-PCR reactions were performed in a thermal The samples were considered positive when the cycler (Techne TC 4000, Cambridge, UK) using ELISA reading was at least twice the reading for CI specific primers CI-5’ (5’- the healthy control [16]. GGCTTCTGAGCAAAGATG-3’) and CI-3’ (5’- CCCAYCAACTGTYGGAAG-3’) [18]. The 2.3 Total RNA Extraction complementary DNA synthesis was done in a PCR tube containing 2 μL of total RNA, 2 μL Total RNA was obtained from fresh leaves of reverse primer (10 mM) and 20 μL of RNAse free infected cucurbit crop as described by [17]. The sterile water. This mix was heated at 70ºC for 2 plant tissues were triturated in 2 volumes of min and cooled for 90 sec. Ten μL of reverse extraction buffer (100 mM Tris-HCl pH 8.0, 50 transcriptase buffer (5X), 2 unit of MMLV-RT mM EDTA, 500 mM sodium chloride and 0.1% 2- (Fermentas), 2 unit of RNAse inhibitor (RNAsin, mercapthoethanol) and centrifuged at low speed Fermentas), 0.6 μL of dNTPs (25 mM) and 20 μL in 2 ml eppendorf tube. After addition of 50 μL of sterile water were added and the mix 20% SDS, the extract was kept at 65ºC for 15 was incubated at 42ºC for 60 min. PCR was

Fig. 2. Map of study area where samples were collected

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performed using 8 μL of Taq DNA polymerase pepo virus isolate from Ekori and L. siceraria buffer (Fermentas), 2 μL of dNTPs (25 mM), 5 virus from Ofodua. Samples were considered units of Taq polymerase (Fermentas), 2 μL of virus positive when the optical density (OD) each primer, 33.6 μL of sterile water and 2 μL of reading at A405nm was twice greater than the the cDNA. PCR reactions were performed by absorbance from healthy controls (Table 1). initial denaturation of 2 min at 94ºC followed by 35 cycles of 30 sec at 94ºC, 30 sec at 53ºC and 3.2 Gel Electrophoresis 2 min at 72ºC. Final extension was 10 min at 72ºC. Ten μL of PCR product were analysed The result for the amplification of the cDNA for using electrophoresis through 1% agarose gel. the potyviruses is shown in Fig. 2. The amplified cDNA bands for lane 1 to 24 corresponded to 2.5 Amplicon Purification, Sequencing 700 bp on the ladder which is the approximate and Sequence Analysis base pair for potyvirus cylindrical inclusion (CI) amplification. The amplicons were purified according to manufacturer’s instructions with the Roche High Lane 1 is Cucumber virus isolate from Calabar, 2 Pure PCR Product Purification Kit. Sequencing is Cucumber virus isolate from Baccocco, 3 is was done by using automated DNA sequencer watermelon virus isolate from Akamkpa, 4 is (Applied Biosystems ABI 310) at Inqaba Biotech watermelon virus isolate from Ehom, 5 is Telfairia (IBWA), Ibadan, Nigeria. The nt virus isolate from Akpet, 6 is Telfairia virus sequences were compared with known isolate from Abini, 7 is Cucurbita pepo virus sequences in the GenBank available at National isolate from Adim, 8 is Cucurbita pepo virus Centre for Biotechnology Information (NCBI) isolate from Iwuru, 9 is Cucurbita pepo virus using the Basic Local Alignment Search isolate from Ekori, 10 is Zeneria spp virus isolate Tool (BLASTn) program from Nko, 11 is Lagenaria siceraria virus isolate (http://www.ncbi.nlm.nih.gov/BLAST/). Sequence from Mkpani, 12 is L. siceraria virus isolate from identities were calculated from the sequence Ofodua, 13 is L. siceraria virus isolate from identity matrix option in MEGA 6 window Ofatura, 14 is virus software [19]. isolate from Okuni, 15 is Trichosanthes Cucumerina virus isolate from Ikom, 16- 3. RESULTS Momordica charantia virus isolate from Ugep, 17

3.1 Serology Test is Cucurbita pepo virus isolate from Afrike, 18 is Zeneria spp virus isolate from Alege, 19 is The results obtained from this test showed that Cucumeropsis mannii virus isolate from Igwo, 20- out 24 samples tested, 20 samples reacted Cucurbita pepo virus isolate from Igoli, 21 is positively against potyvirus specific antiserum Momordica charantia virus isolate from Okuku, while 4 isolate reacted negatively. The samples 22 is Telfairia virus isolate from Sankwala, 23- that reacted positively included Watermelon virus Watermelon virus isolate from Basang, 24 is isolate from Akamkpa, Watermelon virus isolate Momordica charantia virus isolate from Udeshi from Ehom, Telfairia virus isolate from Akpet, while lane H is for healthy control and D is Telfairia virus isolate from Abini, Cucurbita pepo disease sample. virus isolate from Adim, Cucurbita pepo virus isolate from Iwuru, Zeneria spp virus isolate from 3.3 Nucleic Acid Sequencing and Nko, Lagenaria siceraria virus from Mkpani, Sequence Analysis Lagenaria siceraria virus from Ofatura, Trichosanthes Cucumerina from Okuni, A fragment of the predicted size, 700 bp, was Trichosanthes Cucumerina from Ikom, obtained by RT-PCR. Result of gene sequence Momordica charantia from Ugep, Cucurbita pepo analysis showed that the virus isolate from from Afrike, Zeneria spp virus isolate from Alege, watermelon in Akamkpa, L. siceraria isolate from Cucumeropsis mannii from Igwo, Cucurbita pepo Mkpani and Ofatura have 85 to 99% sequence from Igoli, Momordica charantia from Okuku, identity with Morroccan watermelon mosaic virus Telfairia virus isolate from Sankwala, with Genbank accession of KU315179.1. The Watermelon virus isolate from Basang and result further revealed that C. mannii virus isolate Momordica charantia from Udeshi . Samples that from Igwo and watermelon virus isolate from reacted negatively included Cucumber virus Ehom have 85 and 95% sequence identity isolate from Calabar and Baccocco, Cucurbita respectively with Papaya ringspot virus with

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Table 1. Antigen coated plate (ACP) enzyme linked immunosorbent assay (ELISA) for detection of Potyviruses

S/ Host/Isolate Origin Senatorial District OD reading at A405nm N against virus Polyclonal Antibody for Potyvirus 1. Cucumber virus isolate Calabar South 0.321 2. Cucumber virus isolate Baccocco South 0.700 3. Watermelon virus isolate Akamkpa South 1.749* 4. Watermelon virus isolate Ehom South 1.270* 5. Telfairia virus isolate Akpet South 0.986* 6. Telfairia virus isolate Abini South 1.105* 7. C. pepo virus isolate Adim South 0.998* 8. C. pepo virus isolate Iwuru South 1.911* 9. C. pepo virus isolate Ekori Central 0.698 10. Zeneria spp virus isolate Nko Central 1.006* 11. L. siceraria virus isolate Mkpani Central 1.847* 12. L. siceraria virus isolate Ofodua Central 0.177 13. L. siceraria virus isolate Ofatura Central 1.885* 14. T. cucumerina virus isolate Okuni Central 0.981* 15. T. cucumeria virus isolate Ikom Central 1.891* 16. M. charantia virus isolate Ugep Central 0.899* 17. C. pepo virus isolate Afrike North 1.221* 18. Zeneria spp virus isolate Alege North 0.934* 19. C. mannii virus isolate Igwo North 1.001* 20. C. pepo virus isolate Igoli North 1.715* 21. M. charantia virus isolate Okuku North 1.900* 22. Telfairia virus isolate Sankwala North 1.911* 23. Watermelon virus isolate Basang North 0.912* 24. M. charantia virus isolate Udeshi North 1.013* Healthy Control 0.405 Infected Control 1.894 *Sample was considered virus positive when the optical density (OD) reading at A405nm was 2x greater than the absorbance from healthy controls

Fig. 3. Amplification of cDNA bands of isolates testing for cylindrical inclusion (CI) of approximately 700 base paris

Genbank accession of KF033100.1. Again, M. Okuni and Ikom, M. charantia virus isolate from charantia virus isolate from Okuku and Telfairia Ugep, C. pepo virus isolate from Afrike, virus isolate from Akpet and have 88 and 91% Telfairia virus isolate from Sankwala, sequence identity respectively with Zucchini tigre Watermelon virus isolate from Basang and M. mosaic virus with Genbank accession charantia virus isolate from Udeshi have 80 to MN267689.1. Telfairia virus isolate from Abini 92% sequence identity with Algerian watermelon has 90% sequence identity with Potato virus Y mosaic virus with Genbank accession with Genbank accession AF321554.1. C. pepo KU352744.1. Zeneria spp virus isolate from virus isolate from Adim and Iwuru both have 86% Alege and C. pepo virus isolate from Igoli have sequence identity Watermelon mosaic virus with 81 and 91% sequence identity with Soybean KU352744.1 as Genbank accession. Zeneria spp mosaic virus with Genbank accession virus isolate from Nko, T. Cucumerina from HQ396719.1 (Table 2).

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Table 2. Gene sequence analysis with genbank accession number, Host/isolates,% identity and origin of virus isolates

S/N Host/Virus isolate Viruses Origin Senatorial Accession% Identity District Number 1. Watermelon MWMV Akamkpa South KU315179.1 89 2. Watermelon PRSV Ehom South KF033100.1 86 3. Telfairia ZTMV Akpet South MN267689.1 91 4. Telfairia PVY Abini South AF321554.1 90 5. C. pepo WMV Adim South KU352744.1 86 6. C. pepo WMV Iwuru South KU352744.1 86 7. Zeneria AWMV Nko Central KU352744.1 80 8. L. siceraria MWMV Mkpani Central KU315175.1 85 9. L. siceraria MWMV Ofatura Central KU315175.1 87 10. T. Cucumerina AWMV Okuni Central KU352744.1 87 11. T. Cucumerina AWMV Ikom Central KU352744.1 92 12. M. charantia AWMV Ugep Central KU352744.1 83 13. C. pepo AWMV Afrike North KU352744.1 89 14. Zeneria spp SMV Alege North HQ396719.1 81 15. C. mannii PRSV Igwo North KF033100.1 95 16. C. pepo SMV Igoli North HQ396719.1 91 17. M. charantia ZTMV Okuku North MN267689.1 88 18. Telfairia AWMV Sankwa North KU352744.1 81 19. Watermelon AWMV Basang North KU352744.1 81 20. M. charantia AWMV Udeshi North KU352744.1 86

4. DISCUSSION predominant representing 40% of total viruses detected followed by Morroccan watermelon 4.1 Serology Test mosaic virus representing 15% of total viruses detected followed by Papaya ringspot virus, In this study, 24 virus infected leaf samples were Zucchini tigre mosaic virus, Watermelon mosaic obtained from cucurbits grown across major virus and Soybean mosaic virus representing cucurbit growing regions in Cross River State, 10% each for total viruses detected and finally Nigeria. Samples were tested against Antigen Potato virus Y representing 5% of total virus coated plate (ACP) enzyme linked detected. A virus identity will become immunosorbent assay (ELISA), 20 samples unassailable if the degree of homologue of it tested positive against the universal potyvirus sequence is established after comparison with antisera while 4 samples reacted negative. This sequences of previously characterised members result agrees with the work of [12] and [20] who of the genus to which the virus in question reported potyvirus infecting Telfairia occidentalis belongs. Gene sequencing as tool for virus and cucumber respectively using ACP-ELISA as identification and characterization has become diagnostic tool. The result further corroborates the ultimate in recent times [22,23,24]. This result the report by [21] who employed ACP-ELISA in supports the report of [2,25] and [26] who the detection of plant viruses in Dioscorea employed RT-PCR and gene sequence analysis species. in the detection of plant viruses. Report by [27] and [18] have also validated the use of RT-PCR and gene sequence analysis in detecting plant 4.2 RT-PCR and Gene Sequence Analysis viruses in the genus Potyvirus.

The 20 samples were further detected by RT- 5. CONCLUSION PCR with a predicted size of 700 bp using potyvirus cylindrical inclusion (CI) primers. The This study was a survey on occurrence, gene sequence analysis revealed that pathogenicity and identification of viruses Algerian watermelon mosaic virus was infecting some cucurbit crops across major

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cucurbit-growing areas in Cross River State, virus, a new begomovirus associated with Nigeria and was aimed at identifying viruses Bemisia tabaci infestations in Guatemala. infecting cucurbits, ACP-ELISA and RT-PCR International Journal of Plant Pathology. were employing as diagnostic tools. According to 2011;2(4):165-176. the results of this study, 20 out of 24 samples 7. Morse JG, Hoddle MS. Invasion biology of tested positive against universal potyvirus thrips. Annual Review of Entomology. antisera, while results obtained from gene 2006;51:67-89. sequence analysis revealed that cucurbits grown 8. Powell G, Tosh CR, Hardie J. Host plant in Cross River State are severely infected with selection by aphids: Behavioural, AWMV, MWMV, PRSV, PVY, WMV, ZTMV and evolutionary and applied perspectives. SMV. This survey is an accurate and timely Annual Review of Entomology. detection and will form the basis for mitigating 2006;51:309-330. yield losses resulting from virus infection on 9. Lecoq H, Desbiez C. Cucurbit viruses in cucurbits. This research could be adopted as a the mediterranean Region: An ever template for subsequent related researches. changing picture. Advances in Virus Research. 2012;84:67-126. ACKNOWLEDGEMENT 10. Desbiez C, Lecoq H. Zucchini yellow mosaic virus. Plant Pathology. Authors will like to acknowledge the Tertiary 1997;46:809-829. Education Trust Fund (TETFUND), Nigeria for 11. Flock RA, Mayhew DE. Squash leaf curl, a the Institution Based Research (IBR) grant used new disease of cucurbits in California. for this research. We also acknowledge the Plant Disease, 1981;6: 75-76. National Horticultural Research Institute Ibadan, 12. Eyong OI, Owolabi AT, Ekpiken EE, Effa Nigeria for allowing access to their laboratory for EA. First report of algerian watermelon the serological and molecular analysis. mosaic virus infecting Cucumis sativus L in South South Nigeria. Journal of COMPETING INTERESTS Biotechnology and Biochemistry. 2020;42(1):23-33. Authors have declared that no competing 13. Alegbejo MD, Asala S, Kashina BD, interests exist. Banwo O, Shinggu CP. Viruses in weeds in Dioscorea yam fields in Nigeria. African REFERENCES Crop Science Journal. 2014;22:109–115. 14. Ayo-John EI, Hughes JD. Identification of 1. Robinson RW, Decker-Walters DS. Cucumber mosaic virus infecting Musa Cucurbits. CAB International, Wallingford, spp. and vegetable crops in Nigeria. UK; 1997. International Journal of Virology. 2014;10: 2. Hakan F. Occurrence of Alfalfa mosaic 204-210. virus (AMV). Diseases on cucumber crops 15. Owolabi AT, Rabenstein F, Ehrig F. A in Northern Cyprus. Acta horticulturae. strain of Papaya ringspot virus naturally 2012;960:341-346. infecting cucumber (Cucumis sativus L.) in 3. Dhillon MK, Singh R, Naresh JS, Sharma Calabar, South Eastern Nigeria. Nigerian HC. The melon fruit fly, Bactrocera Journal of Botany. 2008;21(1): cucurbitae: A review of its biology and 97-108. management. Journal of Science. 16. Kumar. Methods for the diagnosis of plant 2005;5:1-16. Disease. 2001;85:1027. virus disease. Laboratory manual, IITA 4. HansPetersen HN, McSorley R, Liburd OE. Ibadan, Nigeria; 2009. The impact of intercropping squash with 17. Astruc N, Marcos G, Macquarie GT, non-crop vegetation borders on the above- Candresse, Vicent T. Studies on the ground community. Florida diagnosis of hop stunt viroid in fruit trees: Entomologist. 2010;93:590-608. Identification of new host and application of 5. Peter C, David BV. Population dynamics of a nucleic acid extraction procedure based the pumpkin , Diaphania indica on non_organic solvents. Eur. J. Plant (Saunders) (: Pyralidae). Pathol. 1996;102:837-846. Tropical Pest Management. 1991;37:75- 18. Desbiez C, Joannon B, Wipf_Scheibel C, 79. Chandeysson C, Lecoq H. Emergence of 6. Brown JK, Idris AM, Rogan D, Hussein new strains of watermelon mosaic virus in MH, Palmieri M. Melon chlorotic leaf curl South eastern France: Evidence for limited

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Peer-review history: The peer review history for this paper can be accessed here: http://www.sdiarticle4.com/review-history/69680

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